In a typical irrigation network, water is delivered from a water source to various arterial pipes or branches. The water source delivers the water under pressure to the network. The network includes a number of water emission points, each having a water emission device, such as a drip emitter or sprinkler. The sprinkler type may range from a small, fan-spray nozzle to a large scale rotary nozzle.
A number of factors lead to the use of various sized pipes being used in the irrigation network. The piping components of the network are sized to deliver the desired capacity of water to the watering area. The main delivery pipe is the largest pipe of the network. The water delivered by the main pipe is then divided amongst one or more arterial pipes from which a number of smaller pipes, such as stems, branch off of to deliver water to each of the individual sprinkler heads. If all the pipes of the network were sized similarly, such as to that of the main pipe, the water flow reaching the sprinkler heads would be reduced to such a low pressure, so as not to produce the desired water pattern from the sprinkler head. To address this, it is common for the pipe size to decrease as the pipes branch away from the main pipe.
In a large irrigation network, for instance, every sprinkler is not necessarily in operation at the same time. As an example, a golf course has many different areas that have different irrigation needs. Similarly, a homeowner's yard may have a southern exposure side that receives more sunlight and, thus, requires a greater amount of irrigation than a shaded area. For this reason, the sprinklers may be selectively utilized or activated from area to area throughout the golf course or yard.
At the input, the flow and pressure are designed so that the entire network may be operating at the same time. That is, the irrigation network is designed so that all of the sprinklers may be operating simultaneously. When only a portion of the sprinklers are operating, there is a pressure surplus which can frustrate the desired watering of the system. In addition, a pressure surge or spike at any time during the operation of the irrigation system may cause malfunction of one or more components of the irrigation systems.
One manner of addressing pressure changes is to provide pressure regulators. Often a pressure regulator is positioned within either the stem or in a housing of the sprinkler itself. The pressure regulator may be calibrated for the particular sprinkler, such as through the use of a spring having a specified spring constant, so water is permitted through the sprinkler within a desired range of pressure and flow rate.
As is well-known, pressure or head loss is experienced along the length of any pipe, and throughout the irrigation network. Head loss is also experienced at any point within a piping system where fluid is required to change its flow profile, such as around a corner or elbow, through a filter or filtration device, through a valve, or through a non-uniformity in the pipe size or inner surface. For this reason, a common belief is that the pressure regulator should be located immediately upstream of or within the sprinkler. In other words, the closer the pressure regulator is to the point of emission, the more accurately the pressure can be controlled by the pressure regulator so that the pressure remains in the desired range.
However, positioning of a pressure regulator in the sprinkler itself, or in the stem, is often not appropriate. First, it would require a dedicated pressure regulator for each sprinkler or emission device and calibration of the pressure regulator for that sprinkler or device. Moreover, many sprinkler heads are not traditionally equipped with a pressure regulator due to size restrictions, such as a stem and housing with a relatively small diameter, or with a relatively short length. For a low-flow emitter, such as a bubbler, it is difficult to properly calibrate a pressure regulator for each emitter.
Because of these shortcomings, the pressure regulator may be located upstream of the emission device, such as in a conduit or pipe section of the network. In this manner, the pressure regulator is utilized to control the flow through a number of sprinkler heads and a number of branches of the irrigation network. For a group of low-flow bubblers, it is most effective to control the flow through the group as an entirety. As such, inclusion in the irrigation network contributes additional joints, leading to head loss. Furthermore, although the conduit is typically straight, a configuration which minimizes un-intended head loss therethrough, it adds length to the overall piping.
A typical irrigation network includes control boxes or kits in which a number of control components are located, including, for example, an in-line pressure regulator conduit and a filter unit. The size and number of boxes, which commonly are buried in the ground, are selected depending on the system requirements.
Current pressure regulators utilize a vent to the atmosphere. More specifically, these pressure regulators utilize a valve member which shifts against the bias of a spring in the face of a force difference on opposite portions of the valve member. This requires a pressure sink, such as the atmosphere, to be located on one side of the valve member while the other side is exposed to the pressure of the water flow. One example of such a prior art pressure regulator is disclosed in U.S. Pat. No. 5,779,148, to Saarem, et al. (“the '148 patent”). In the '148 patent, the pressure regulator includes a vent communicating both with an otherwise sealed cavity surrounding a shifting member and with the atmosphere by passing between a housing and a seal.
Alternatively, when the pressure regulator is located in a control box, the pressure vent communicates with the interior of the box itself. In other forms, the pressure regulator may simply rely on a seal, such as that disclosed in the '148 patent that permits communication therethrough but is less than perfect in preventing ingress of dirt or particulate matter.
Assembling and securing currently known pressure regulators also presents a number of issues. By way of example, the '148 patent utilizes a shoulder within the housing to restrict the upward motion of the pressure regulator. During downward motion of the shifting member, the apparent means of preventing shifting of the pressure regulator as a whole within the housing is the pressure experienced from the water flow itself. It is noted that the ‘shoulder’ is not at a right angle, instead being more of a ramped surface, such that pressure on the pressure regulator forces the housing to expand, forces the regulator to move upward, and creates stress concentrations on the housing. Expansion of the housing itself reduces the efficacy of the seals between the pressure regulator and the interior of the housing, which may allow the vent to the atmosphere to receive water and/or pressure, such that the desired function of the pressure regulator is lost. This tends to result with the sprinkler providing water in an undesirable manner.
In other pressure regulators, a different means of retention may be provided. The regulators are typically installed from the bottom of the sprinkler housing or a riser therein. The pressure regulator has an inlet positioned to face the incoming water flow into the sprinkler, typically at a bottom end, and an outlet positioned in the direction of the outgoing water flow. The retention device or structure is used to prevent downward expulsion or shifting of the pressure regulator from the housing, which may occur due to a negative pressure that sometimes occurs when a portion or entirety of a network is shut off. The retention device is inserted into the housing at a bottom portion of the pressure regulator.
Accordingly, there has been a need for an improved device for regulating pressure throughout portions of a fluid delivery network, such as an irrigation system.